code: def is_dask_series_or_df(
      df: DataFrame, backend: Optional["Backend"]
  ) -> bool:  # noqa: F821
      if is_dask_backend(backend):
          import dask.dataframe as dd
  
          return isinstance(df, dd.Series) or isinstance(
              df, dd.DataFrame
          )
      return False
  
file_path: ludwig/ludwig/utils/dataframe_utils.py
imports: from typing import Dict, List, Optional, Tuple
  import numpy
  import pandas
  from ludwig.api_annotations import DeveloperAPI
  from ludwig.constants import DASK_MODULE_NAME
  from ludwig.data.dataframe.base import DataFrameEngine
  from ludwig.utils.types import DataFrame
label_desc: Use image node_id 3 for calling a global function with example usage: is_dask_series_or_df(df, backend) and returns: False, unknown